I receive following error on click of a custom button

missing;before statement

the custom button is created for creating a task automatically using the foll Javascript code:

{!REQUIRESCRIPT("("/soap/ajax/17.0/connection.js")} var t1= new sforce.SObject("Task"); t1.Assigned To = "r1free@fantailtech.com"; t1.Subject = "ABC283"; t1.Name = "abcd"; t1.Status = "Not Started"; t1.Priority = "Normal";result = sforce.connection.create([t1]);